_____ with what they were like 15 years ago, home PCs are cheape

_____ with what they were like 15 years ago, home PCs are cheaper, faster, and have a much bigger memory.
A、Compare
B、Comparing
C、Compared
D、Having Compared
【正确答案】：C
【题目解析】：答案选C。独立主格结构，home PCs是逻辑主语，应该是被比较，所以用过去分词形式。